High- $Q$ Narrowband Tunable Combline Bandpass Filters Using MEMS Capacitor Banks and Piezomotors

TLDR: In this article, a new class of evanescent tunable combline bandpass filters based on electronic tuning with the use of RF microelectromechanical systems (RF-MEMS) capacitor banks and also mechanical tuning using piezomotors is presented.

Abstract: This paper presents the design and implementation of a new class of evanescent tunable combline bandpass filters based on electronic tuning with the use of RF microelectromechanical systems (RF-MEMS) capacitor banks and also mechanical tuning using piezomotors The use of microelectromechanical systems tuning circuit results in compact implementation of the proposed filters with high-Q and near to zero dc power consumption The proposed filter structures consist of combline resonators with tuning disks that are either mechanically moveable using piezomotors or are loaded with RF-MEMS capacitor banks Two- and six-pole tunable bandpass filters are designed and measured based on the proposed tuning concept The two-pole tunable filter operates at 25 GHz with a bandwidth of 22 MHz and demonstrates a tuning range of 110 MHz, while the quality factor is better than 374 (1300-374 over the tuning range) The six-pole tunable filter with RF-MEMS capacitor banks operates from 2634 to 259 GHz (44-MHz tuning range) The proposed tunable filter structures can also be implemented using alternative technologies such as barium-strontium-titanate varactors